The present invention pertains to fans for cooling electronic equipment and more particularly to such a fan in which speed is controlled to maintain relatively constant equipment temperature and substantially reduce unnecessary acoustical noise.
While variable speed or thermostatically controlled fans have been proposed heretofore, prior controller designs have not been well suited for integration with the axial flow fans which are specifically designed for cooling electronic equipment. Further, these prior art systems have not, in general, been responsive to the actual needs of an overall or complete system, particularly when such a system is to be installed in an office environment.
One problem which is engendered by the use of cooling fans for electronic equipment used in an office environment is the noise which such fans can generate. This problem is compounded by the tendency of electronic equipment designers to provide cooling for so-called worst case conditions. In other words, the designer will typically include sufficient air flow capacity to deal with the densest system configuration, most heavily loaded on the hottest expected day. The air flow theoretically required for such worst case conditions will typically be much more than that required under typical or nominal conditions and the fans specified to provide such capability will generate excessive and unnecessary noise. It is, however, very important to assure sufficient cooling capacity since electronic systems, particularly those employing solid state components, are subject to various failures upon overheating.
Among the several objects of the present invention may be noted the provision of a fan system which will sufficiently cool electronic equipment to ensure high reliability; the provision of such a system which is readily integrated with the type of fans typically employed for cooling electronic components; the provision of such a system which is highly reliable and which is of relatively simple and inexpensive construction. Other objects and features will be in part apparent and in part pointed out hereinafter.